1. Field of the Invention
The present invention relates generally to the field of chemical gas and liquid containment and delivery systems. More specifically, the present invention relates to an apparatus and process for safely secondarily containing at least two supply cylinders containing a hazardous fluid substance and delivering the hazardous fluid substance such as chlorine gas from the supply cylinders either simultaneously or sequentially, to a receiving structure or system, such as to one or more distribution cylinders or to a pool chlorine gas treatment system in accordance with government regulations. These regulations specifically include Toxic Gas Ordinance No. 23450, Chapter 17.78 of the San Jose Municipal Code, and the Uniform Fire Code, Article 20, Hazardous Materials.
The apparatus includes a high pressure containment vessel for receiving and safely enclosing a plurality of, and preferably two, supply cylinders each having a release valve and containing a hazardous fluid substance at a pressure above ambient. The containment vessel contains a cylinder support structure for supporting the at least two supply cylinders on support rollers so that the supply cylinders can be rolled into and out of the containment vessel. A high pressure flex line or rigid pipe fitting extends from each supply cylinder release valve to one of two automatic gas sensing valve assemblies mounted in a vessel port in the vessel wall for the specific supply cylinder. A gas sensing valve assembly is provided on each release valve and automatically shuts off the flow of gas through the given vessel port when a gas leak is detected outside the containment vessel. Chlorine gas passes through each valve assembly and into a receiving structure or system, such as a gas manifold having coupling ports to which one or more distribution cylinders, also known as service cylinders, are removably connected. A back-up, manually operated valve is also provided in series with each automatic gas sensing valve assembly. Each gas sensing valve assembly has a fail-safe-to-close design and the back-up valve is fitted with quick-turn lever handled Hastaloy(trademark) xe2x80x9cCxe2x80x9d ball valves. The sensing and back-up valves both have reduced-orifice controllers. A containment vessel support structure is provided having a vessel pivot assembly so that the vessel can be tilted back, causing liquid chlorine within the contained cylinders to flow to the bottom of the cylinders and away from cylinder release valves. The cylinders are loaded into the vessel while the vessel is horizontal, but have to be oriented at an angle, preferably at 45 degrees, to drain gas rather than liquid. The containment vessel has a spring-loaded vessel lid biased by lid springs to an open position to aid in opening the vessel lid when the vessel is tilted back, and door sealing means are provided.
To meet secondary containment requirements, the gas manifold is enclosed within an exhausted enclosure connected to a gas scrubbing unit. The scrubbing unit is substantially smaller than scrubbers typically used in the industry, because most of the gas is automatically sealed within the supply cylinders by the sensing valve assembly and within any distribution cylinders by a reduced orifice flow controller on the manifold coupling ports. Should one or both of the supply cylinders leak, the gas then contain may be released into the scrubbing unit at a very low rate, and alternatively may be released instead into at least one gas cylinder rather than scrubbed and wasted.
The delivery process is inventively passive, so that dependence upon electric power for safe containment and flow is eliminated. The process includes the steps of placing two supply cylinders into a containment vessel; and connecting the supply cylinder release valves to respective tubing means extending through fluid substance sensing valve assemblies in the vessel wall. Optional additional steps include delivery of the fluid substance from the gas sensing valve assemblies into a gas manifold; and delivering the gas from the manifold into a distribution cylinder. Fluid substance contained within the supply vessel and gas manifold is maintained at ambient temperature so that gas pressure is minimized for safe retention.
2. Description of the Prior Art
There have long been gas delivery and transfer systems for delivering hazardous fluid substances from a supply cylinder, which is typically a one ton cylinder, into a receiving structure or system, such as a distribution cylinder, which is typically a fifteen or twenty pound cylinder. Government environmental and safety regulations have required that delivery or transfer take place within secondary containment. This has been accomplished in the chlorine industry in several ways.
One way has been to make the transfer in a room filled with massive and very costly scrubber equipment, so that if a leak develops, all gas in the supply cylinder can be very rapidly scrubbed from the air. This process makes it necessary to shut down operation in the room for one or more days and also results in the loss of all chlorine in the supply cylinder, both of these consequences being very expensive in addition to the cost of the scrubbing equipment. Should leakage take place during a power outage, particularly during a natural disaster, the scrubbing equipment would not function, so that the dangerous chlorine gas would escape into the neighborhood and into nearby ecosystems.
Another way of transferring chlorine gas has been with the use of what is known as a xe2x80x9ccoffinxe2x80x9d, which is essentially an ordinary sheet metal cabinet. The supply cylinder and distribution cylinder are both placed inside the coffin. The coffin has a release port opening into a powerful suction and scrubber assembly. In the event of supply cylinder leakage, the scrubber assembly must be activated immediately to rapidly draw away all of the escaping gas which includes the entire contents of the supply cylinder. The coffin would not contain the gas in the event that a power failure shut down the scrubber. Thus the problems of the scrubbing room are substantially presented by the coffin and scrubber containment system. Containment buildings and hoods are not capable of withstanding the pressure and corrosive nature of suddenly released quantities of chlorine gas.
Yet another and highly improved way, invented by the present applicant, has involved secondarily containing a supply cylinder within a high pressure vessel and gradually draining off the chlorine gas it contains. In the event of supply cylinder catastrophic failure, the secondary containment vessel retains the gas indefinitely and safely until it can be drained into secure vessels or scrubbed. See Caparros, U.S. Pat. No. 5,607,384, issued on Mar. 4, 1997 and U.S. Pat. No. 5,819,787, issued on Oct. 13, 1998, the contents of which are incorporated by reference. A problem with this approach has been that only one supply cylinder can be contained and drained at a time for each containment vessel.
Other prior references include Van Valkenburgh, et al., U.S. Pat. No. 5,511,908, issued on Apr. 30, 1996 and Payne, et al., U.S. Pat. No. 5,735,639, issued on Apr. 7, 1998 which disclose mobile structures providing a form of secondary containment of hazardous gases stored within cylinders inside the mobile structures. These mobile structures are very bulky, and do not provide storage pressure driven evacuation of leaked gas into another primary container.
Cartwright, et al., U.S. Pat. No. 6,006,588, issued on Dec. 28 1999 and McGouran, Jr., U.S. Pat. No. 4,911,326, issued on Mar. 27, 1990, teach secondary containment boxes with removable side walls for receiving toxic gas primary containers. Gas escaping from the primary containers is confined within interstitial spaces between the primary vessel and the surrounding secondary containment box for subsequent release into a detoxifying system (Cartwright) or the secondary containment box is simply xe2x80x9ccleanedxe2x80x9d (McGouran, Jr., column 4, line 13).
Karwacki, et al., U.S. Pat. No. 5,569,151, issued on Oct. 29, 1996 reveals a secondary containment and scrubbing system. Rather than providing a close-fitting, high pressure secondary container, Karwacki, et al. discloses a secondary container which is xe2x80x9clarge enough to contain the entire contents of the inner vesselxe2x80x9d and also contains means to absorb and scrub leaked gas. Karwacki, et al. appears highly cumbersome and can contain only one supply cylinder at a time.
It is thus an object of the present invention to provide a hazardous fluid substance delivery system which provides the safe secondary containment required by law for multiple supply cylinders for containment with greater economy.
It is another object of the present invention to provide such a system which is compact and which requires minimal shutdown time in the event of a fluid substance leak.
It is another object of the present invention to provide such a system which safely retains any of the fluid substance leaking from one or more of the secondarily contained supply cylinders which has not reached the receiving structure or system, for gradual release into gas cylinders or into a scrubbing unit.
It is another object of the present invention to provide such a system which can release gaseous substances at a slow, controlled rate and thus requires only a small, low capacity and inexpensive scrubbing assembly.
It is still another object of the present invention to provide such a system which safely and secondarily contains the vast majority of leaking fluid substance in a containment vessel in the event of power failure such as during a natural disaster.
It is yet another object of the present invention to provide such a containment vessel, which is mounted to tilt backward so that the supply cylinders are partially upright, causing liquid chlorine within the contained cylinders to flow to the bottom of the cylinders and away from cylinder release valves.
It is still another object of the present invention to provide such a system which automatically stops the flow of fluid substance from the containment vessel with a valve operated by a fluid substance sensing mechanism.
It is finally an object of the present invention to provide such a system which delivers or transfers a fluid substance by passive, low pressure means and which is compact and economical to build and operate.
The present invention accomplishes the above-stated objectives, as well as others, as may be determined by a fair reading and interpretation of the entire specification.
An apparatus is provided for safely delivering a hazardous fluid substance to a receiving structure, including first and second supply cylinders containing the fluid substance and each supply cylinder having a supply cylinder release port; a high pressure containment vessel having a vessel wall and being sized to receive and safely enclose the first and second supply cylinders; first and second high pressure first tubes extending from the first and second supply cylinders, and in fluid communication with the supply cylinder release port and extending to and being in fluid communication with a vessel port in the vessel wall; and a vessel valve in fluid communication with each of the first tube for controlling delivery of the fluid substance from the first and second supply cylinders and from the vessel. The apparatus preferably additionally includes a cylinder support structure within the containment vessel for supporting the first and second supply cylinders and retaining the supply cylinders against substantial movement within and relative to each other. The cylinder support structure preferably includes a lower lateral cross-plate within the containment vessel and at least two parallel and longitudinally oriented cylinder support rails mounted to the lower lateral cross-plate, the lateral cross-plate being secured at each end to the vessel wall; and a series of support rollers rotatably mounted to the cylinder support rails to support and permit the supply cylinders to roll on the rollers into and out of the vessel.
The vessel valve preferably includes a fluid substance sensing valve assembly mounted at the vessel port, for automatically shutting off the flow of the fluid substance upon detection of the fluid substances outside the containment vessel, for automatically sealing substantially all of the fluid substance contained within the supply cylinder within the containment vessel in the event of an uncontrolled release of the fluid substance outside the containment vessel. The apparatus may additionally include at least one distribution cylinder; where the receiving structure includes a distribution manifold in fluid communication with the tube through which the fluid substance passes, having at least one port to which the at least one distribution cylinder is removably connected, the manifold having a certain manifold internal volume for containing a certain quantity of the fluid substance; an exhausted enclosure enclosing the manifold and being of sufficient internal volume to retain at substantially ambient pressure and temperature the certain quantity of fluid substance contained within the manifold; and a fluid substance scrubbing unit of sufficient capacity to scrub all the fluid substance initially within the supply cylinder at a controlled flow rate through the vessel valve. The vessel valve preferably includes a valve adaptor having a reduced orifice controller.
The apparatus preferably additionally includes a containment vessel support structure including a support frame having two substantially parallel and laterally spaced apart frame side beams, pin bearings secured onto tops of the frame side beams, vessel pins extending laterally from the vessel side wall and through the pin bearings, so that the vessel is pivotable relative to the frame on the vessel pins.